PySide6.QtCore.QXmlStreamWriter¶

class QXmlStreamWriter¶

The QXmlStreamWriter class provides an XML 1.0 writer with a simple streaming API.

Details

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

QXmlStreamWriter is the counterpart to QXmlStreamReader for writing XML. It is compliant with the XML 1.0 specification and writes documents using XML 1.0 syntax, escaping rules, and character validity constraints.

Note

XML 1.1 is not supported. While version strings may be set manually in the output, documents requiring features specific to XML 1.1, such as additional control characters cannot be produced using this class.

Like its related class, it operates on a QIODevice specified with setDevice() . The API is simple and straightforward: for every XML token or event you want to write, the writer provides a specialized function.

You start a document with writeStartDocument() and end it with writeEndDocument() . This will implicitly close all remaining open tags.

Element tags are opened with writeStartElement() followed by writeAttribute() or writeAttributes() , element content, and then writeEndElement() . A shorter form writeEmptyElement() can be used to write empty elements, followed by writeAttributes() .

Element content consists of either characters, entity references or nested elements. It is written with writeCharacters() , which also takes care of escaping all forbidden characters and character sequences, writeEntityReference() , or subsequent calls to writeStartElement() . A convenience method writeTextElement() can be used for writing terminal elements that contain nothing but text.

The following abridged code snippet shows the basic use of the class to write formatted XML with indentation:

stream = QXmlStreamWriter(output)
stream.setAutoFormatting(True)
stream.writeStartDocument()            ...

stream.writeStartElement("bookmark")
stream.writeAttribute("href", "http://qt-project.org/")
stream.writeTextElement("title", "Qt Project")
stream.writeEndElement() # bookmark            ...

stream.writeEndDocument()

QXmlStreamWriter takes care of prefixing namespaces, all you have to do is specify the namespaceUri when writing elements or attributes. If you must conform to certain prefixes, you can force the writer to use them by declaring the namespaces manually with either writeNamespace() or writeDefaultNamespace() . Alternatively, you can bypass the stream writer’s namespace support and use overloaded methods that take a qualified name instead. The namespace http://www.w3.org/XML/1998/namespace is implicit and mapped to the prefix xml.

The stream writer can automatically format the generated XML data by adding line-breaks and indentation to empty sections between elements, making the XML data more readable for humans and easier to work with for most source code management systems. The feature can be turned on with the autoFormatting property, and customized with the autoFormattingIndent property.

Other functions are writeCDATA() , writeComment() , writeProcessingInstruction() , and writeDTD() . Chaining of XML streams is supported with writeCurrentToken() .

QXmlStreamWriter always encodes XML in UTF-8.

If an error occurs while writing, hasError() will return true. However, by default, data that was already buffered at the time the error occurred, or data written from within the same operation, may still be written to the underlying device. This applies to Encoding , InvalidCharacter , and user-raised Custom . To avoid this and ensure no data is written after an error, use the stopWritingOnError property. When this property is enabled, the first error stops output immediately and the writer ignores all subsequent write operations. Applications should treat the error state as terminal and avoid further use of the writer after an error.

The QXmlStream Bookmarks Example illustrates how to use a stream writer to write an XML bookmark file (XBEL) that was previously read in by a QXmlStreamReader .

Synopsis¶

Methods¶

def __init__()
def autoFormatting()
def autoFormattingIndent()
def device()
def error()
def errorString()
def hasError()
def raiseError()
def setAutoFormatting()
def setAutoFormattingIndent()
def setDevice()
def setStopWritingOnError()
def stopWritingOnError()
def writeAttribute()
def writeAttributes()
def writeCDATA()
def writeCharacters()
def writeComment()
def writeCurrentToken()
def writeDTD()
def writeDefaultNamespace()
def writeEmptyElement()
def writeEndDocument()
def writeEndElement()
def writeEntityReference()
def writeNamespace()
def writeProcessingInstruction()
def writeStartDocument()
def writeStartElement()
def writeTextElement()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

class Error¶

This enum specifies the different error cases that can occur when writing XML with QXmlStreamWriter .

Constant

Description

QXmlStreamWriter.Error.Error.None_

No error has occurred.

QXmlStreamWriter.Error.Error.IO

An I/O error occurred while writing to the device.

QXmlStreamWriter.Error.Error.Encoding

An encoding error occurred while converting characters to the output format.

QXmlStreamWriter.Error.Error.InvalidCharacter

A character not permitted in XML 1.0 was encountered while writing.

QXmlStreamWriter.Error.Error.Custom

A custom error has been raised with raiseError() .

Constant	Description
QXmlStreamWriter.Error.Error.None_	No error has occurred.
QXmlStreamWriter.Error.Error.IO	An I/O error occurred while writing to the device.
QXmlStreamWriter.Error.Error.Encoding	An encoding error occurred while converting characters to the output format.
QXmlStreamWriter.Error.Error.InvalidCharacter	A character not permitted in XML 1.0 was encountered while writing.
QXmlStreamWriter.Error.Error.Custom	A custom error has been raised with `raiseError()` .

Added in version 6.10.

__init__()¶

Constructs a stream writer.

See also

setDevice()

__init__(array)

Parameters:: array – QByteArray

Constructs a stream writer that writes into array. This is the same as creating an xml writer that operates on a QBuffer device which in turn operates on array.

__init__(device)

Parameters:: device – QIODevice

Constructs a stream writer that writes into device;

autoFormatting()¶

Return type:: bool

Returns true if auto formatting is enabled, otherwise false.

See also

setAutoFormatting()

autoFormattingIndent()¶

Return type:: int

See also

setAutoFormattingIndent()

device()¶

Return type:: QIODevice

Returns the current device associated with the QXmlStreamWriter , or None if no device has been assigned.

See also

setDevice()

error()¶

Return type:: Error

Returns the current error state of the writer.

If no error has occurred, this function returns None .

See also

errorString() hasError()

errorString()¶

Return type:: str

If an error has occurred, returns its associated error message.

The error message is either set internally by QXmlStreamWriter or provided by the user via raiseError() . If no error has occured, this function returns a null string.

See also

error() hasError()

hasError()¶

Return type:: bool

Returns true if an error occurred while trying to write data.

If the error is IO , subsequent writes to the underlying QIODevice will fail. In other cases malformed data might be written to the document.

The error status is never reset. Writes happening after the error occurred may be ignored, even if the error condition is cleared.

See also

error() errorString() raiseError(const QString &message)

raiseError(message)¶

Parameters:: message – str

Raises a custom error with the given message.

This function is for manual indication that an error has occurred during writing, such as an application level validation failure.

See also

errorString() error() hasError()

setAutoFormatting(enable)¶

Parameters:: enable – bool

Enables auto formatting if enable is true, otherwise disables it.

The default value is false.

See also

autoFormatting()

setAutoFormattingIndent(spacesOrTabs)¶

Parameters:: spacesOrTabs – int

See also

autoFormattingIndent()

setDevice(device)¶

Parameters:: device – QIODevice

Sets the current device to device. If you want the stream to write into a QByteArray , you can create a QBuffer device.

See also

device()

setStopWritingOnError(stop)¶

Parameters:: stop – bool

See also

stopWritingOnError()

stopWritingOnError()¶

Return type:: bool

See also

setStopWritingOnError()

writeAttribute(attribute)¶

Parameters:: attribute – QXmlStreamAttribute

Writes the attribute.

This function can only be called after writeStartElement() before any content is written, or after writeEmptyElement() .

writeAttribute(qualifiedName, value)

Parameters:

qualifiedName – str
value – str

Writes an attribute with qualifiedName and value.

This function can only be called after writeStartElement() before any content is written, or after writeEmptyElement() .

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeAttribute(namespaceUri, name, value)

Parameters:

namespaceUri – str
name – str
value – str

Writes an attribute with name and value, prefixed for the specified namespaceUri. If the namespace has not been declared yet, QXmlStreamWriter will generate a namespace declaration for it.

This function can only be called after writeStartElement() before any content is written, or after writeEmptyElement() .

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeAttributes(attributes)¶

Parameters:: attributes – QXmlStreamAttributes

Writes the attribute vector attributes. If a namespace referenced in an attribute not been declared yet, QXmlStreamWriter will generate a namespace declaration for it.

This function can only be called after writeStartElement() before any content is written, or after writeEmptyElement() .

See also

writeAttribute() writeNamespace()

writeCDATA(text)¶

Parameters:: text – str

Writes text as CDATA section. If text contains the forbidden character sequence “]]>”, it is split into different CDATA sections.

This function mainly exists for completeness. Normally you should not need use it, because writeCharacters() automatically escapes all non-content characters.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeCharacters(text)¶

Parameters:: text – str

Writes text. The characters “<”, “&”, and “”” are escaped as entity references “<”, “&, and “"”. To avoid the forbidden sequence “]]>”, “>” is also escaped as “>”.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

See also

writeEntityReference()

writeComment(text)¶

Parameters:: text – str

Writes text as XML comment, where text must not contain the forbidden sequence -- or end with -. Note that XML does not provide any way to escape - in a comment.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeCurrentToken(reader)¶

Parameters:: reader – QXmlStreamReader

Writes the current state of the reader. All possible valid states are supported.

The purpose of this function is to support chained processing of XML data.

See also

tokenType()

writeDTD(dtd)¶

Parameters:: dtd – str

Writes a DTD section. The dtd represents the entire doctypedecl production from the XML 1.0 specification.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeDefaultNamespace(namespaceUri)¶

Parameters:: namespaceUri – str

Writes a default namespace declaration for namespaceUri.

If writeStartElement() or writeEmptyElement() was called, the declaration applies to the current element; otherwise it applies to the next child element.

Note that the namespaces http://www.w3.org/XML/1998/namespace (bound to xmlns) and http://www.w3.org/2000/xmlns/ (bound to xml) by definition cannot be declared as default.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeEmptyElement(qualifiedName)¶

Parameters:: qualifiedName – str

Writes an empty element with qualified name qualifiedName. Subsequent calls to writeAttribute() will add attributes to this element.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeEmptyElement(namespaceUri, name)

Parameters:

namespaceUri – str
name – str

Writes an empty element with name, prefixed for the specified namespaceUri. If the namespace has not been declared, QXmlStreamWriter will generate a namespace declaration for it. Subsequent calls to writeAttribute() will add attributes to this element.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

See also

writeNamespace()

writeEndDocument()¶

Closes all remaining open start elements and writes a newline.

See also

writeStartDocument()

writeEndElement()¶

Closes the previous start element.

See also

writeStartElement()

writeEntityReference(name)¶

Parameters:: name – str

Writes the entity reference name to the stream, as “&``name``;”.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeNamespace(namespaceUri[, prefix={}])¶

Parameters:

namespaceUri – str
prefix – str

Writes a namespace declaration for namespaceUri with prefix. If prefix is empty, QXmlStreamWriter assigns a unique prefix consisting of the letter ‘n’ followed by a number.

If writeStartElement() or writeEmptyElement() was called, the declaration applies to the current element; otherwise it applies to the next child element.

Note that the prefix xml is both predefined and reserved for http://www.w3.org/XML/1998/namespace, which in turn cannot be bound to any other prefix. The prefix xmlns and its URI http://www.w3.org/2000/xmlns/ are used for the namespace mechanism itself and thus completely forbidden in declarations.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeProcessingInstruction(target[, data={}])¶

Parameters:

target – str
data – str

Writes an XML processing instruction with target and data, where data must not contain the sequence “?>”.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeStartDocument()¶

Writes a document start with XML version number “1.0”.

See also

writeEndDocument()

writeStartDocument(version)

Parameters:: version – str

Writes a document start with the XML version number version.

Note

This function does not validate the version string and allows setting it manually. However, QXmlStreamWriter only supports XML 1.0. Setting a version string other than “1.0” does not change the writer’s behavior or escaping rules. It is the caller’s responsibility to ensure consistency between the declared version and the actual content.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

See also

writeEndDocument()

writeStartDocument(version, standalone)

Parameters:

version – str
standalone – bool

Writes a document start with the XML version number version and a standalone attribute standalone.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

See also

writeEndDocument()

writeStartElement(qualifiedName)¶

Parameters:: qualifiedName – str

Writes a start element with qualifiedName. Subsequent calls to writeAttribute() will add attributes to this element.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeStartElement(namespaceUri, name)

Parameters:

namespaceUri – str
name – str

Writes a start element with name, prefixed for the specified namespaceUri. If the namespace has not been declared yet, QXmlStreamWriter will generate a namespace declaration for it. Subsequent calls to writeAttribute() will add attributes to this element.

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeTextElement(qualifiedName, text)¶

Parameters:

qualifiedName – str
text – str

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Writes a text element with qualifiedName and text.

This is a convenience function equivalent to:

writeStartElement(qualifiedName)
writeCharacters(text)
writeEndElement()

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .

writeTextElement(namespaceUri, name, text)

Parameters:

namespaceUri – str
name – str
text – str

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Writes a text element with name, prefixed for the specified namespaceUri, and text. If the namespace has not been declared, QXmlStreamWriter will generate a namespace declaration for it.

This is a convenience function equivalent to:

writeStartElement(namespaceUri, name)
writeCharacters(text)
writeEndElement()

Note

In Qt versions prior to 6.5, this function took QString , not QAnyStringView .